Pro/Forums - View Single Post - Digidoc 5

logosmani · 06-05-2003, 07:17 AM

k, shame that

well, my problem is that i use the digidoc to raise the speed on my fans, not turn them on as such. The fans are always on on a low voltage, but when the temperature rises the digidoc powers a relay which switches the fans to full throttle. Unfortunately it does that on/off thing a lot and the sound the relay makes going on and off so much is far worse than anything my fans ever put out.

Although i was thinking looking at the 555 in the monostable/one shot setup looks good 'as is' (from the link above) i wasn't sure if the circuit shown starts the timer from when the input switch is released (ie. off) or if it starts it from its initial make. In otherwords, will it, if the digidoc keeps the 'fan' on for longer than the timed delay its set for turn the fan off? or will it perhaps turn it off + then on again everytime the delay expires + is then refreshed? that make sense?

can anyone with 555 experience help with that question?

06-05-2003, 07:17 AM	#10
logosmani Cooling Neophyte Join Date: Apr 2003 Location: Scotland Posts: 47	k, shame that well, my problem is that i use the digidoc to raise the speed on my fans, not turn them on as such. The fans are always on on a low voltage, but when the temperature rises the digidoc powers a relay which switches the fans to full throttle. Unfortunately it does that on/off thing a lot and the sound the relay makes going on and off so much is far worse than anything my fans ever put out. Although i was thinking looking at the 555 in the monostable/one shot setup looks good 'as is' (from the link above) i wasn't sure if the circuit shown starts the timer from when the input switch is released (ie. off) or if it starts it from its initial make. In otherwords, will it, if the digidoc keeps the 'fan' on for longer than the timed delay its set for turn the fan off? or will it perhaps turn it off + then on again everytime the delay expires + is then refreshed? that make sense? can anyone with 555 experience help with that question? Last edited by logosmani; 06-05-2003 at 07:26 AM.